• Biomolecules & Therapeutics
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• v.2 no.1
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• pp.39-46
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• 1994

The present study was undertaken to demonstrate whether or not bradykinin activates a phospholipase D in rabbit kidney proximal tubule cells. By measuring the formation of [$^3$H]phosphatidic acid and [$^3$H]phosphatidylethanol we could elucidate the direct stimulation of phospholipase D by bradykinin. Bradykinin leads to a rapid increase in [$^3$H]phosphatidic acid and [$^3$H]diacylglycerol, and [$^3$H]phosphatidic acid formation preceded the formation of [$^3$H]diacylglycerol. This result suggests that some phosphatidic acid seems to be formed directly from phosphatidylcholine by the action of phospholipase D, not from diacylglycerol by the action of diacylglycerol kinase. In addition, the other mechanisms by which phospholipase D is activated was examined. We have found that phospholipase D was activated and regulated by extracellular calcium ion and pertussis toxin-insensitive G protein, respectively. It has also been shown that bradykinin may activate phospholipase D through protein kinase C-dependent pathway. In conclusion, we are now, for the first time, strongly suggesting that bradykinin-induced activation of phospholipase D in the rabbit kidney proximal tubule cells is mediated by a pertussis toxin-insensitive G protein and is dependent of protein kinase C.

• YAKHAK HOEJI
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• v.27 no.4
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• pp.249-256
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• 1983

When the reaction rate constant k of phospholipase D on liposome was measured by the ANS fluorometry, k of phospholipase D on DMPC liposome which was made of L-$\alpha$-PI, cholesterol and L-$\alpha$-PS decreased than that of phospholipase D on DMPC liposome with cholesterol or with PI and cholesterol. Optimal $Ca^{2+}$ concentration, the most important factor on effect of phospholipase D, also decreased to 1mM, as compared with 10mM and 60mM respectively when cholesterol and PI were added, and cholesterol only was added. The change of cholesterol Mol% had a great influence on k value of phospholipase D. But in case of addition of L-$\alpha$-PS to cholesterol, the influence was relatively diminished.

• Journal of Microbiology and Biotechnology
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• v.12 no.2
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• pp.189-195
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• 2002

Using Streptomyces sp. YU100 isolated from Korean soil, the fermentative production of phospholipase D was attempted along with its purification and characterization studies. When different carbon and nitrogen sources were supplemented in the culture medium, glucose and yeast extract were found to be the best. By varying the concentration of nutrients and calcium carbonate, the optimal culture medium was determined as 2.0% glucose, 1.5% yeast extract, 0.5% tryptone 0.3% calcium carbonate. During cultivation, the strain secreted most of the phospholipase D in the early stage of growth within 24 h. The phospholipase D produced in the culture broth exhibited hydrolytic activity as well as transphosphatidylation activity on lecithin (phosphatidylcholine). In particular, the culture broth showed 8.7 units/ml of hydrolytic activity when cultivated at $28^{\circ}C$ for 1.5 days. The phospholipase D was purified using 80% ammonium sulfate precipitation and DEAE-Sepharose CL-6B column chromatography, which produced a major band of 57 kDa on a 10% SDS-polyacrylamide gel with purity higher than 80%. The enzyme showed an optimal pH of 7 in hydrolytic reaction, and at pH 4 in a transphosphatidylation reaction. The enzyme activity increased until the reaction temperature was elevated to $60^{\circ}C$. The enzyme was relatively stable at high temperatures and neutral pH, but significantly unstable in the alkaline range. Among the detergents tested as emulsifiers of phospholipids, the highest enzyme activity was observed when 1.5% Triton X-100 was employed. However, no inhibitory effect by metal ions was detected. Under optimized reaction conditions, the purified enzyme not only completely decomposed PC to phosphatidic acid within 1 h, but also exhibited higher than 80% conversion rate of PC to PS by transphosphatidylation within 4 h.

• Parasites, Hosts and Diseases
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• v.49 no.1
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• pp.1-8
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• 2011

The pathogenesis and pathophysiology of Acanthamoeba infections remain incompletely understood. Phospholipases are known to cleave phospholipids, suggesting their possible involvement in the host cell plasma membrane disruption leading to host cell penetration and lysis. The aims of the present study were to determine phospholipase activities in Acanthamoeba and to determine their roles in the pathogenesis of Acanthamoeba. Using an encephalitis isolate (T1 genotype), a keratitis isolate (T4 genotype), and an environmental isolate (T7 genotype), we demonstrated that Acanthamoeba exhibited phospholipase $A_2$ (PLA$_2$). and phospholipase D (PLD) activities in a spectrophotometry-based assay. Interestingly, the encephalitis isolates of Acanthamoeba exhibited higher phospholipase activities as compared with the keratitis isolates, but the environmental isolates exhibited the highest phospholipase activities. Moreover, Acanthamoeba isolates exhibited higher PLD activities compared with the PLA$_2$. Acanthamoeba exhibited optimal phospholipase activities at $37^{\circ}C$ and at neutral pH indicating their physiological relevance. The functional role of phospholipases was determined by in vitro assays using human brain microvascular endothelial cells (HBMEC), which constitute the blood-brain barrier. We observed that a PLD-specific inhibitor, i.e., compound 48/80, partially inhibited Acanthamoeba encephalitis isolate cytotoxicity of the host cells, while PLA$_2$-specific inhibitor, i.e., cytidine 5'-diphosphocholine, had no effect on parasite-mediated HBMEC cytotoxicity. Overall, the T7 exhibited higher phospholipase activities as compared to the T4. In contract, the T7 exhibited minimal binding to, or cytotoxicity of, HBMEC.

• Microbiology and Biotechnology Letters
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• v.22 no.4
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• pp.333-339
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• 1994

In order to screen microorganisms producing phospholipase D (PLD) [EC 3.1.4.4], culture broths of about 900 strains of soil bacteria were subjected to examine for the PLD activity. When the hydrolytic activity of PLD (H-activity) in the supernatant was determined, 64 strains produced PLD more than 0.3 unit/ml and all of them were actinomycetes. Among 26 culture broths tested, 6 ones had transphosphatidylation activity (T-activity) of 30~68%. When the strains except one were cultivated on 3 different media at 30$\circ$C for 3 days under aerobic condition, strain # 1090 on medium B (yeast extract 1%, peptone 1%, glucose 1.5%, glycerol 1%, CaCO$_{3}$ 0.4%, and pH 7.2) produced PLD with much higher H- and T-activity, which were 8.3 units/ml and 76.3%, respectively. Subsequently, time course of PLD production of the strain # 1090 during cultivation with aeration of 1 v/v/m and agitation of 400 rpm at 30$\circ$C for 5 days on medium B in jar fermentor was investigated. H-activty of PLD reached almost maximum (about 9 units/ml) after 32 hours and maximal T-activity was found to be about 80%.

• Bulletin of the Korean Chemical Society
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• v.23 no.10
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• pp.1451-1489
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• 2002

Sphingosine is known to regulate a wide range of cell physiology including growth, differentiation, and apoptosis. In this study, we examined the effect of sphingosine on the phospholipase D (PLD) activity in rat thymocytes. Sphingosine potently stimulated PLD in the absence of extracellular calcium, while depletion of intracellular calcium by BAPTA/AM treatment completely blocked activation of PLD by sphingosine. Sphingosine-induced increase of the intracellular calcium concentration was confirmed using a fluorescent calcium indicator Fluo-3/AM. A phosphoinositide-specific phospholipase C inhibitor U73122 partially inhibited the stimulation of PLD by sphingosine. When mouse PLD2 gene was transfected into mouse thymoma EL4 cells, which lack intrinsic PLD activity, sphingosine could stimulate PLD2 significantly while overexpression of human PLD1 had no effect. Taken together, the sphingosine-stimulated PLD activity in rat thymocytes is dependent on the mobilization of intracellular calcium and appears to be due to the PLD2 isoform.

• Journal of Pharmacopuncture
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• v.4 no.2
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• pp.5-15
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• 2001

This study was carried out for production of neutral antibody to bee venom $(anti-phospholipase\;A_2IgY)$. Hen layings were injected repeatedly with bee venom and phospholipase $A_2$ with Freund's adjuvant. Specific antibody in egg yolk from immunized hen laying was separated, and purified, also immunological characteristics of anti phospholipase $A_2\;IgY$ was invested. The results were summarized as follows: 1. Phospholipase $A_2$ was showed single band at molecular weight 17,000 in SDS-PAGE and bee venom was showed two band at molecular weight 17,000 and under molecular weight 6,500 in SDS-PAGE. 2. During 70 days after hen immunized with bee venom and phospholipase $A_2$, antibodies(anti-bee venom IgY) to bee venom were showed poor ELISA value in egg yolk, but antibodies$(anti-Phospholipase\;A_2IgY)$ to phospholipase $A_2$ in egg yolk were increased ELISA value from 8 days or 15 days and found maximum ELISA value at 42 days. Also after booster at 49 days, ELISA value of anti Phospholipase $A_2\;IgY$ in egg yolk was supported at optical density(O.D) 1.0 level, continuously. 3. Titer of phospholipase $A_2\;IgY$ was showed 1: 32,000. 4. In double immunodiffusion test to phospholipase $A_2$ after double dilution of anti-phospholipase $A_2\;IgY$, only precipitation line was made in 1:1 dilution well of anti-Phospholipase $A_2\;IgY$. But In immunodiffusion test to anti-phospholipase $A_2\;IgY$ after double dilution of phospholipase $A_2$, Precipitation line to 250ul/ml well of phospholipase $A_2$ was showed. In double immunodiffusion test to bee venom(1mg/ml) after double dilution anti-phospholipase $A_2\;IgY$, all well without 1:32 dilution well were showed strong precipitation line. 5. In dot bloting test to anti-phospholipase $A_2\;IgY$ after diluting bee venom(0.5mg/ml), dot bloting color was showed clearly to $1/100(5{\mu}g/ml)$ in bee venom.

• Journal of Life Science
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• v.24 no.12
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• pp.1378-1382
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• 2014

Phospholipase D (PLD) catalyzes the hydrolysis of phospholipid to phosphatidic acid (PA), a lipid secondary messenger. Two forms of PLD isozymes, phosphatidylcholine-specific PLD1 and PLD2, have been identified. PLD has emerged as a critical regulator of cell proliferation and survival signaling, and dysregulation of PLD occurs in a various illnesses, including cancer. PLD activity is essential for cell survival and protection from apoptosis. Overexpression of PLD isozymes or PLD-generated PA attenuates the expression of apoptotic genes and confers resistance to apoptosis. The apoptosis-related molecular mechanisms of PLD remain largely unknown. Recently, the dynamics of PLD turnover during apoptosis have been reported. The cleavage of PLD isozymes as specific substrates of caspase differentially regulates apoptosis. PLD1 is cleaved at one internal site, and PLD2 is cleaved two sites at the front of the N-terminus. The cleavage of PLD1 reduces its enzymatic activity, probably via the dissociation of two catalytic motifs, whereas the cleavage of PLD2 does not affect the catalytic motifs and its activity. Thus, PLD2 maintains antiapoptotic capacity, despite its cleavage. Therefore, the differential cleavage pattern of PLD isozymes by caspase affects its enzymatic activity and antiapoptotic function. Thus, PLD is considered a potential target for cancer therapy. We summarize recent studies regarding the functional role of PLD in apoptosis.

• The Korean Journal of Physiology and Pharmacology
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• v.14 no.6
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• pp.427-433
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• 2010

This study was conducted to investigate the effects of extremely low frequency electromagnetic fields (EMF) on signal pathway in plasma membrane of cultured cells (RAW 264.7 cells and RBL 2H3 cells), by measuring the activity of phospholipase $A_2$ ($PLA_2$), phospholipase C (PLC) and phospholipase D (PLD). The cells were exposed to the EMF (60 Hz, 0.1 or 1 mT) for 4 or 16 h. The basal and $0.5\;{\mu}M$ melittin-induced arachidonic acid release was not affected by EMF in both cells. In cell-free $PLA_2$ assay, we failed to observe tbe change of $cPLA_2$ and $sPLA_2$ activity. Also both PLC and PLD activities did not show any change in the two cell lines exposed to EMF. This study suggests that the exposure condition of EMF (60 Hz, 0.1 or 1 mT) which is 2.4 fold higher than the limit of occupational exposure does not induce phospholipases-associated signal pathway in RAW 264.7 cells and RBL 2H3 cells.

• Proceedings of the Korean Society of Applied Pharmacology
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• 1995.04a
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• pp.58-58
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• 1995

식물에서부터 새로운 소염작용제를 개발하기 위하여 여러식물을 대상으로 염증반응의 초기단계에서 중요한 역할을 하는 것으로 알려진 Phospholipase $A_2$에 저해활성을 갖는 물질을 검색하였고 그 중 강한 억제활성을 보인 유근피에서 유효성분을 분리하였다. 유근피의 에칠 아세테이트 분획에 대하여 실리카겔 크로마토그래피, Sephadex LH-20 크로마토그래피, 분취 박막 크로마토그래피를 수행하여 phenol성 -OH기를 갖는 활성성분인 PSH-II-84-1를 분리하였다. $^1$H-NMR 신호의 양상과 짝지움 상수 값에서 분리된 물질은 (+)-catechin 의 당 유도체로 확인되었다. $^{13}$C-NMR 자료를 분석하여 치환된 당은 D-apiofuranose로 확인되었다. 방향족환의 $^{l3}$C-NMR 신호들은 extended Huekel theory를 응용하여 얻은 net charge 계산 값과 상관시켜 할당하였다. 이상의 구조연구 결과 이 물질은 (+)-catechin-7-0-$\beta$-D-apiofuranoside로 밝혀졌다. (+)-catechin-7-0-$\beta$-D-apiofuranoside의 효소억제활성은 Type II Phospholipase $A_2$에 대하여 $IC_{50}$/이 600$\mu$M이었다.다.